1. Field of the Invention
This invention relates in general to electronic systems and in particular to power supplies for electronic systems.
2. Description of the Related Art
Computer systems are information handling electronic systems which can be designed to give independent computing power to one user or a plurality of users. Computer systems may be found in many forms including, for example, mainframes, minicomputers, workstations, servers, personal computers, internet terminals, notebooks, and embedded systems. Personal computer (PC) systems, such as the International Business Machines (IBM)((trademark)) compatible PC systems, include desk top, floor standing, or portable versions. A typical PC system includes a processor, associated memory and control logic, and a number of peripheral devices that provide input and output for the system. Such peripheral devices often include display monitors, keyboards, mouse-type input devices, floppy and hard disk drives, CD-ROM drives, network capability cards, terminal devices, modems, televisions, sound devices, voice recognition devices, electronic pen devices, and mass storage devices such as tape drives, CD-R drives or DVDs. Other types of computer systems may include some of these peripheral devices.
Computer systems and other electronic systems typically include power supplies for supplying operating power to the components of the system. A power supply for an electronic system may implement one of a number of power supply converter topologies. Examples of converter topologies include linear and switching converter topologies such as buck, boost, push-pull, fly-back, and forward converter topologies.
Placing a power supply in a nonoperating mode and then quickly placing it in an operating mode such as during a reboot operation may cause problems in a computer system in that the voltage level of the power supply output may not decay to an operably zero voltage level prior to the restart of the computer system. Because reboot and other startup routines typically assume that the power supply output voltage is initially zero when the computer system is started up, rebooting when the power supply output is at a xe2x80x9cnonzeroxe2x80x9d value may cause problems in the rebooting process such as causing the processor to lock or freeze or cause the corruption of data.
Some prior art power supplies have included a timer circuit to provide a timed delay for restarting a power supply. However, adding a timer increases the complexity of a restart circuit. Furthermore, because the delay is predetermined, the delay in restarting may last longer than necessary or not long enough.
It has been discovered that providing an electronic system with a restart circuit that delays the restart of a power supply until an output of the power supply is in compliance with a specified parameter advantageously restarts a power supply when the power supply output is at a level, such as a specific voltage level, to sufficiently ensure that components of the electronic system powered by the power supply are properly reset.
In one aspect of the invention, a restart circuit includes a comparison circuit for determining whether an output of a power supply is in compliance with a specified parameter. The restart circuit also includes an input to receive a request to place the power supply in an operating mode and an output to provide a signal to place the power supply in an operating mode in response to the request if the comparison circuit determines that the output of the power supply is in compliance with the specified parameter.
In another aspect of the invention, a computer system includes a power supply. The power supply has an output for supplying power to components of the computer system. The computer system also includes a restart circuit that places the power supply in an operating mode in response to receiving via an input a request to place the power supply in an operating mode and in response to a determination that the output of the power supply is in compliance with a specified parameter.
In another aspect of the invention, a method for placing a power supply in an operating mode includes receiving a request to place a power supply in an operating mode from a nonoperating mode and determining whether an output of the power supply is in compliance with a specified parameter. The method also includes placing the power supply in an operating mode in response to receiving the request and in response to a determination that the output of power supply is in compliance with the specified parameter.
In another aspect of the invention, a computer system includes a power supply for supplying power to components of the computer system and means for delaying the restart of the power supply until an output of the power supply is determined to be in compliance with a specified parameter.